/**
*      author: Y_Yao
*      created: 2025-04-03 14:22:50
**/

#include<bits/stdc++.h>

#define int LL
using namespace std;
using LL = long long;
const LL LLINF = 9e18;
const int INF = 0x3f3f3f3f;
const int N = 1e5 + 7;
int x;
int a[N];

void solve()
{
    cin >> x;
    int cur = 0;
    int time = 0;
    while(cur < x)
    {
        time++;
        cur += time;
    }
    cout << time << endl;
}

signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);

    int t = 1;
    // cin >> t;
    while(t--)
    {
        solve();
    }
    return 0;
}